尼日利亚石—塔菲石—黑铝镁铁矿及相关系列矿物的晶体结构构筑原理

从氧原子最紧密堆积以及阳离子充填四面体和八面体空隙原理出发 ,以简单氧化物矿物最紧密堆积结构类型金绿宝石、尖晶石、铁钒矿为基础 ,深入讨论了复杂氧化物矿物最紧密堆积结构类型彭志忠石、尼日利亚石、塔菲石、黑铝镁铁 (钛 )矿等晶体结构构筑原理。以O表示全部为阳离子八面体配位的层 ;以T层表示阳离子八面体配位与阳离子四面体配位的混合层 ,其中T1表示阳离子八面体配位与一种方向阳离子四面体配位的混合层 ,T2 表示阳离子八面体配位与两种方向阳离子四面体配位的混合层。这类矿物晶体结构可用O、T1、T2 堆积方式表征 ,O层与T层交替排列。如 :彭志忠石 ( 6H)的晶体结构表示为…OT2 OT1OT1… ,塔菲石 ( 8H)的晶体结构表示为…OT2 OT1OT2 OT1… ,尼日利亚石 ( 2 4R)的晶体结构表示为…OT1OT2 OT2 OT1…× 3 ,等等 ;它们的晶体结构中既有尖晶石的…OT2 OT2 …晶体结构单位 ,又有铁钒矿的…OT1OT1…晶体结构单位。

THE PRINCIPLE OF CONSTRUCTING THE CRYSTAL STRUCTURES OF NIGERITE-TAAFFEITE- HOGBOMITE AND THEIR RELATED MINERALS

According to the principle of closest packing of oxygen and the principle of cations filling tetrahedral and octahedral cavities and based on the types of closest packing structure of simple oxides such as chrysoberyl, spinel and nolanite, this paper discusses in detail the crystal structure constructing principle of the closest packing structure types of complex oxide minerals such as pengzhizhongite, nigerite, taaffeite, hogbomite, etc. O expresses the layers of all octahedral-coordination cations; T indicates the mixed layers of tetrahedral- and octahedral-coordination cations: T1 stands for the mixed layers of octahedral-coordination cations and one-direction tetrahedral-coordination cations; T2 expresses the mixed layers of octahedral-coordination cations with two-direction tetrahedral-coordination cations. The crystal structure of the mineral can be expressed by O, T1, and T2 packing. O alternates with T. For example, the crystal structure of pengzhizhongite (6H) can be expressed by …OT2OT1OT1…; taaffeite (8H), …OT2OT1OT2OT1…; and nigerite (24R), …OT1OT2OT2OT1…×3. In their structures, there not only have the crystal structure units of spinel …OT2OT2…; but also have the units of nolanite…OT1OT1….